Leviticus 13:31

And after looking at the diseased place, if it does not seem to go deeper than the skin, and there is no black hair in it, then the priest will have him shut up for seven days:

Treasury of Scripture Knowledge

Summary

And if the priest look on the plague of the scall, and, behold, it be not in sight deeper than the skin, and that there is no black hair in it; then the priest shall shut up him that hath the plague of the scall seven days:

Seven days

Bible References

Seven days

Leviticus 13:4
But if the mark on his skin is white, and does not seem to go deeper than the skin, and the hair on it is not turned white, then the priest will keep him shut up for seven days;

Basic English, produced by Mr C. K. Ogden of the Orthological Institute - public domain